The present invention relates to a glucoamylase gene, to a method for isolating such gene, and to a host which is transformed by an expression vector of said gene and produces glucoamylase.
The techniques of genetic engineering have been successfully applied to the pharmaceutical industry, resulting in a number of novel products. Increasingly, it has become apparent that the same technologies can be applied on a larger scale to the production of enzymes of value to other industries. The benefits of achieving commercially useful processes through genetic engineering are expected to include: (1) cost savings in enzyme production, (2) production of enzymes in organisms generally recognized as safe which are more suitable for food products, and (3) specific genetic modifications at the DNA level to improve enzyme properties such as thermal stability and other performance characteristics.
One important industrial application of genetic engineering involves improving the ability of industrial yeast strains to degrade complex carbohydrate substrates such as starch. Yeasts such as Saccharomyces cerevisiae which are suitable for alcoholic fermentation do not produce an enzyme capable of hydrolyzing starch to utilizable substrates. Currently, starch used as a food source in alcoholic fermentation must be saccharified, either chemically or enzymatically in a separate process to produce utilizable substrates for the fermenting yeast.
It would thus be desirable to construct, by genetic recombination methods, a fermentation yeast such as S. cerevisiae which itself has the capacity to synthesize one or more enzymes capable of breaking down starch to utilizable substrates. European patent application No. 0,034,470 discloses preparing recombinant DNA containing an amylase encoding gene by cleaving a bacterial donor microorganism to obtain DNA and inserting those fragments in a vector. The amylase enzymes produced from the DNA which are used to hydrolyze starch are preferably alpha-amylase, beta-amylase or a pullulanase.